Ink jet printers typically provide ink to the printheads by means of an ink jet cartridge. The cartridge provides a storage well in which printing ink is stored until used with the printheads. The ink jet cartridge is connected to the printhead so as to allow flow of ink from the cartridge to the printhead when needed.
Currently, filled ink jet cartridges are produced by first forming the main body of the cartridge. The main body constitutes a bottom and four side walls defining an ink cavity of the ink jet cartridge. A foam piece is then typically pressed into the body cavity of the cartridge, and the cavity and foam piece are then filled with ink by means of an open-ended top. Lastly, a cover is placed on the now ink filled main body and attached to the side walls thereto. Typically this attachment is made by means of an ultrasonic weld which may vibrate the cartridge at a frequency of 20 to 40 kHz. The weld completely seals the cover to the side walls of the ink jet cartridge.
This process suffers from several drawbacks. Most importantly, the ink is agitated by the vibration of the ultrasonic welding process. Vibrating the ink filled cartridge at such high frequencies tends to produce and entrain small air bubbles in the ink. These bubbles in turn can cause problems with print quality. Additionally, the process completely seals the top of the ink jet cartridge allowing no gas flow. Therefore, an equalization vent must be formed somewhere else on an upper portion or cover of the cartridge to allow the pressure in the cartridge to equalize with the ambient pressure outside of the cartridge to ensure proper ink flow. The size of the hole and the path of gas flow through it must be carefully controlled so as to prevent the ink from being spilled or evaporating in significant quantities. However, the vent hole must allow enough gas flow for inside and outside gas pressures to equalize.
It is an object of the invention to provide an improved ink jet cartridge.
It is another object of the invention to provide a method for assembling an ink jet cartridge which reduces air bubble formation in the ink.
A further object of the invention is to provide an ink jet cartridge having improved venting for gas pressure equalization.